Low molecular weight polytetrafluoroethylene (also referred to as “polytetrafluoroethylene wax” or “polytetrafluoroethylene micro powder”) having a molecular weight of several thousands to several hundreds of thousands has excellent chemical stability and a very low surface energy, as well as low fibrillatability. Thus, low molecular weight polytetrafluoroethylene is used as an additive for improving the smoothness and the texture of film surfaces in production of articles such as plastics, inks, cosmetics, coatings, and greases (for example, see Patent Literature 1).
Examples of known methods for producing low molecular weight polytetrafluoroethylene include polymerization, radiolysis, and pyrolysis.
With regard to the radiolysis among these techniques, Patent Literature 2 discloses a method for producing polytetrafluoroethylene powder having an average particle size of 200 micrometers or smaller, including irradiating polytetrafluoroethylene powder or a preformed article or article thereof with ionizing radiation of at least 5×105 röntgen, and then pulverizing the irradiated article.
Patent Literature 3 discloses a method for providing a friable polytetrafluoroethylene product having particles of a desired size including a) maintaining a polytetrafluoroethylene starting material at below 18.89° C. (66° F.) during handling prior to irradiation; b) mixing the polytetrafluoroethylene starting material at below 18.89° C. (66° F.) with a wetting agent to provide a mixture; and c) irradiating at least a portion of the mixture to provide a wetted polytetrafluoroethylene product having particles of the desired size or being readily comminutable without agglomeration to particles of the desired size.
Patent Literature 4 discloses a method for producing polytetrafluoroethylene resin wax, including irradiating polytetrafluoroethylene resin with ionizing radiation in the presence of a gas mixture of an oxygen component and a halomethane.